1. Technical Field
The present invention relates to electronic systems, and more particularly, to portable electronic systems having power supplies that use two power sources, for example a battery and an alternating current (AC) adaptor.
2. Related Art
One type of electronic system is a computer system. Computer systems are information handling systems that are utilized by many individuals and businesses today. A computer system can be defined as a microcomputer that includes a central processing unit (CPU), a volatile memory, a non-volatile memory such as read only memory (ROM), a display monitor, a keyboard, a mouse or other input device such as a trackball, a floppy diskette drive, a compact disc-read only memory (CD-ROM) drive, a modem, a hard disk storage device, a printer, and other peripherals. A computer system's main board, which is a printed circuit board known as a motherboard, is used to electrically connect these components together. A computer system can be a desktop computer, a portable computer such as a notebook computer or palm-sized computer, or other type of computer.
The central processing unit is often described as a microprocessor. The microprocessor is an electronic component having internal logic circuitry handling most, if not all, the data processing in the computer system. The internal logic circuitry of microprocessors is typically divided into three functional parts known as the input/output (I/O) unit, the control unit, and the arithmetic-logic unit (ALU). These three functional parts interact together and determine the power and performance of the microprocessor. The combination of the control unit and the arithmetic-logic unit can be referred to as the central processing unit. Also, the combination of the input/output unit, the control unit, and the arithmetic-logic unit can be referred to as the central processing unit.
One example of non-volatile memory is read only memory (ROM). Information stored in non-volatile memory can remain unchanged even when there is a power failure. The information stored in non-volatile memory will stay there until it is changed. Read only memory is used to store important information such as instructions for the central processing unit. There are different types of read only memory including electrically-erasable-programmable-read-only-memory (EEPROM) chip and flash-read-only-memory (flash-ROM). The flash-ROM can also be referred to as flash memory.
Computer systems include a basic input output system (BIOS) which is an especially important program stored in read only memory. The basic input output system tests a computer every time the computer is powered on. The basic input output system can allocate a computer system's resources automatically, making adjustments needed to accommodate new hardware. Also, the basic input output system governs how system board components interact.
When the computer system is powered on, the basic input output system immediately takes control of the computer system and its components. The first duty of the basic input output system is to perform a series of diagnostic routines called the power on self test (POST) routine, which ensures that every part of the computer system's hardware is functioning properly.
An electronic system, such as a computer system, can receive power from two or more sources. For example, the electronic system can be connected to a first power source which is an alternating current (AC) power source supplying alternating current power and can be also connected to a second power source which is a battery supplying a direct current (DC) power. One potential setup would allow the electronic system to receive power from the AC power source when the AC power source is available, and to receive power from the battery at times when the AC power source is not available. In view of this configuration, there is an urgent need for an efficient power control arrangement in order to prevent a wasteful flow of a reverse current that might otherwise be caused by a voltage difference between the two power sources.
I have found that an inefficient use of power in electronic systems can be extremely inconvenient and wasteful. Efforts have been made to improve a supply of power in electronic systems.
Exemplars of recent efforts in the art include U.S. Pat. No. 5,200,685 for adapter for external battery and battery system issued to Sakamoto, U.S. Pat. No. 5,184,025 for computer-controlled uninterruptible power supply issued to McCurry et al., U.S. Pat. No. 5,578,876 for unique computer power system with backup power issued to Crampton, U.S. Pat. No. 5,715,156 for method and apparatus for providing AC or DC power for battery powered tools issued to Yilmaz et al., and U.S. Pat. No. 5,592,030 for power supply for energizing DC load from AC or DC source issued to Adahan.
While these recent efforts provide advantages, I note that they fail to adequately provide a battery powered electronic system with a sufficiently improved power efficiency.